Hard Star Battle answer — October 3, 2025

Full written solution

Every deduction from the walkthrough above, in order. Each technique is explained in the Star Battle strategy guide.

1. Starting position — the grid is split into regions (bold outlines). Each row, column, and region needs exactly two stars, and no two stars may touch.
2. 3-cell region rule: Middle cell can't hold a star (row 1, column 2).
3. Region completion: 2 stars needed, 2 candidates (row 1, column 1).
4. Mark 2 cells adjacent to stars as X (row 2, column 1).
5. Region completion: 1 star needed, 1 candidate (row 1, column 3).
6. Mark 3 cells adjacent to stars as X (row 1, column 4).
7. Row 1 complete: Mark 5 remaining cells as X (row 1, column 5).
8. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 4, column 1).
9. Three candidates with two adjacent: Isolated candidate must hold a star (row 5, column 1).
10. Mark 4 cells adjacent to stars as X (row 4, column 2).
11. Column 1 complete: Mark 4 remaining cells as X (row 3, column 1).
12. Region completion: 1 star needed, 1 candidate (row 3, column 2).
13. Mark 2 cells adjacent to stars as X (row 3, column 3).
14. Clump analysis (Row 2): candidate clumps can only just supply the remaining stars (row 3, column 6).
15. Clump analysis (Row 5): each clump must supply its full share of stars (row 4, column 6).
16. Mark 7 cells adjacent to stars as X (row 3, column 5).
17. Region completion: 1 star needed, 1 candidate (row 5, column 8).
18. Mark 6 cells adjacent to stars as X (row 4, column 8).
19. Row completion: 1 star needed, 1 candidate (row 4, column 4).
20. Mark 3 cells adjacent to stars as X (row 3, column 4).
21. Row completion: 1 star needed, 1 candidate (row 3, column 9).
22. Mark 2 cells adjacent to stars as X (row 2, column 8).
23. Three candidates in a row: Middle cell can't hold a star (row 2, column 6).
24. Region completion: 2 stars needed, 2 candidates (row 2, column 5).
25. Region completion: 1 star needed, 1 candidate (row 2, column 7).
26. Clump analysis (Row 6): candidate clumps can only just supply the remaining stars (row 7, column 3).
27. Clump analysis (Column 2): candidate clumps can only just supply the remaining stars (row 8, column 3).
28. Three candidates with two adjacent: Isolated candidate must hold a star (row 8, column 2).
29. Mark 3 cells adjacent to stars as X (row 7, column 2).
30. Region completion: 1 star needed, 1 candidate (row 6, column 3).
31. Mark 1 cell adjacent to stars as X (row 6, column 4).
32. Three candidates in a row: Middle cell can't hold a star (row 7, column 8).
33. Row completion: 2 stars needed, 2 candidates (row 7, column 7).
34. Mark 4 cells adjacent to stars as X (row 6, column 6).
35. Region completion: 1 star needed, 1 candidate (row 6, column 5).
36. Row completion: 1 star needed, 1 candidate (row 7, column 9).
37. Mark 1 cell adjacent to stars as X (row 8, column 9).
38. Region complete: Mark 1 remaining cell as X (row 9, column 9).
39. Column 5 complete: Mark 2 remaining cells as X (row 8, column 5).
40. Region completion: 1 star needed, 1 candidate (row 8, column 4).
41. Mark 1 cell adjacent to stars as X (row 9, column 4).
42. Column completion: 1 star needed, 1 candidate (row 9, column 6).
43. Mark 1 cell adjacent to stars as X (row 9, column 7).
44. Region completion: 1 star needed, 1 candidate (row 9, column 8).
45. Solved! Every row, column, and region has its two stars, none touching.